# US 10,478,796 B2 · Control of fouling in high pressure polyethylene manufacture

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- Number: US 10,478,796 B2
- Document ID: US10478796B2
- Status: Granted
- Kind: B2
- Application number: 15/573,974
- Filed: 2016-05-13
- Published: 2018-10-11
- Granted: 2019-11-19
- Earliest claimed: 2015-06-30
- Assignees: ExxonMobil Chemical Patents Inc.
- Applicants: ExxonMobil Chemical Patents Inc.
- Inventors: Henri A. Lammens; Paul J. Clymans; Philip H. Cornelissen
- Web page: https://patentgrep.com/patent/US10478796B2

## CPC

- B01J 19/002: {Avoiding undesirable reactions or side-effects, e.g. avoiding explosions, or improving the yield by suppressing side-reactions}
- B01J 4/008: {Feed or outlet control devices}
- B01J 19/0013: {Controlling the temperature of the process}
- B01J 19/06: Solidifying liquids (making microcapsules B01J13/02)
- B01J 19/2415: {Tubular reactors}
- C08F 2/00: Processes of polymerisation
- C08F 2/01: characterised by special features of the polymerisation apparatus used
- C08F 2/34: Polymerisation in gaseous state
- C08F 10/02: Ethene
- C08F 110/02: Ethene
- B01J 2219/00006: Large-scale industrial plants
- B01J 2219/0004: Processes in series
- B01J 2219/00094: Jackets
- B01J 2219/00159: controlling multiple zones along the direction of flow, e.g. pre-heating and after-cooling
- B01J 2219/00162: controlling the pressure
- B01J 2219/00247: Fouling of the reactor or the process equipment
- Y02P 30/40: Ethylene production
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

Systems and processes for controlling fouling in the manufacture of ethylene polymers and copolymers at high pressure. Disclosed is a high pressure polyethylene polymerization system comprising a reactor, a primary compressor, and a secondary compressor, the secondary compressor comprising: a) a first stage, wherein the first stage comprises at least two cylinders, and the discharge pipes of the at least two cylinders are fluidly connected by a first stage discharge cross-connect pipe; b) a second stage; c) an interstage; and d) a first cooler applied to the interstage piping starting at a location within 10 meters downstream of the first stage discharge cross-connect pipe.

## Claims

### Claim 1

A high pressure polyethylene polymerization system comprising a reactor, a primary compressor, and a secondary compressor, the secondary compressor comprising:
a. a first stage, wherein the first stage comprises at least two cylinders, and the discharge pipes of the at least two cylinders are fluidly connected by a first stage discharge cross-connect pipe;
b. a second stage;
c. an interstage; and
d. a first cooler applied to the interstage piping at a location within 10 meters downstream of the first stage discharge pipe cross-connect.

### Claim 2 (depends on 1)

The system of claim 1, wherein the first stage comprises at least four cylinders, and the discharge pipes of the at least four cylinders are fluidly connected by a first stage discharge pipe cross-connect.

### Claim 3 (depends on 1)

The system of claim 1, wherein the first cooler is applied at a location immediately downstream of the first stage discharge pipe cross-connect.

### Claim 4 (depends on 1)

The system of claim 1, wherein the first cooler is a cooling jacket or a heat exchanger.

### Claim 5 (depends on 1)

The system of claim 1, wherein the second stage comprises at least two cylinders, and the suction pipes of the at least two cylinders are fluidly connected by a second stage suction cross-connect pipe.

### Claim 6 (depends on 1)

The system of claim 1, wherein the second stage comprises at least four cylinders, and the suction pipes of the at least four cylinders are fluidly connected by a second stage suction cross-connect pipe.

### Claim 7 (depends on 5)

The system of claim 5, wherein the first cooler is a cooling jacket and the cooling jacket ends at a location within 10 meters upstream of the second stage suction pipe cross-connect.

### Claim 8 (depends on 5)

The system of claim 5, wherein the first cooler is a cooling jacket and the cooling jacket ends at a location immediately upstream of the second stage suction pipe cross-connect.

### Claim 9 (depends on 1)

The system of claim 1, wherein the second stage comprises at least two cylinders, and the discharge pipes of the at least two cylinders in the second stage are fluidly connected by a second stage discharge cross-connect pipe.

### Claim 10 (depends on 1)

The system of claim 1, wherein the second stage comprises at least four cylinders, and the discharge pipes of the at least four cylinders are fluidly connected by a second stage discharge cross-connect pipe.

### Claim 11 (depends on 9)

The system of claim 9, wherein a second cooler is applied to the interstage piping at a location within 10 meters downstream of the second stage discharge pipe cross-connect.

### Claim 12 (depends on 9)

The system of claim 9, wherein a second cooler is applied to the interstage piping at a location immediately downstream of the second stage discharge pipe cross-connect.

### Claim 13 (depends on 11)

The system of claim 11, wherein the second cooler is a cooling jacket or a heat exchanger.

### Claim 14 (depends on 11)

The system of claim 11, wherein the second cooler is a cooling jacket and the cooling jacket ends at a location within 10 meters upstream of an entrance to the reactor.

### Claim 15 (depends on 11)

The system of claim 11, wherein the second cooler is a cooling jacket and the cooling jacket ends at a location immediately upstream of an entrance to the reactor.

### Claim 16

A high pressure polyethylene polymerization process comprising:
a. providing a feed stream comprising ethylene;
b. compressing the feed stream in a primary compressor;
c. further compressing the feed stream in a secondary compressor, wherein the secondary compressor comprises a first stage and a second stage, and wherein the first stage and second stage each comprise at least two cylinders and discharge pipes, and the discharge pipes of the at least two cylinders of the first stage are fluidly connected by a first stage discharge cross-connect pipe;
d. cooling the compressed feed stream at a location within 10 meters downstream of the first stage discharge cross-connect pipe; and
e. feeding the compressed feed stream to a polymerization reactor.

### Claim 17 (depends on 16)

The polymerization process of claim 16, wherein an operating discharge temperature of the first stage cylinders is substantially maintained at or below 85° C. and an operating discharge temperature of the second stage cylinders is substantially maintained at or below 60° C.

### Claim 18 (depends on 16)

The polymerization process of claim 16, wherein an operating discharge temperature of the first stage cylinders is substantially maintained at or below 95° C. and an operating discharge temperature of the second stage cylinders is substantially maintained at or below 80° C.

### Claim 19 (depends on 16)

The polymerization process of claim 16, wherein no modifier is added to polymerization process.

### Claim 20 (depends on 16)

The polymerization process of claim 16, wherein a modifier is added to polymerization process.

### Claim 21 (depends on 20)

The polymerization process of claim 20, wherein the modifier is an aldehyde.

### Claim 22 (depends on 20)

The polymerization process of claim 20, wherein the modifier is selected from the group consisting of at least one of acetaldehyde, propionaldehyde, butyraldehyde, and mixtures thereof.

### Claim 23 (depends on 20)

The polymerization process of claim 20, wherein the modifier is a C2 to C20 unsaturated modifier.

### Claim 24 (depends on 20)

The polymerization process of claim 20, wherein the modifier is a C2 to C20 saturated modifier.

### Claim 25 (depends on 20)

The polymerization process of claim 20, wherein the modifier concentration in a process stream within the secondary compressor is maintained at or greater than 0.1 mole %, based on the total moles of the process stream.